Crustal investigation of the Hellenic subduction zone using wide aperture seismic data

Bohnhoff, Marco; Makris, J.; Papanikolaou, D.; Stavrakakis, G.

doi:10.1016/s0040-1951(01)00264-5

Cited by 140 publications

(174 citation statements)

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“…This fault zone consists of three branches misleadingly called Ptolemeus, Pliny and Strabo 'trenches' (indicated by dotted arrows in Figure 10). The term 'trench' is misleading as these structures do not represent subduction trenches as observed at various forearcs of subduction zones worldwide but, in contrast were identified as deep-sea depressions with wedge-shaped sedimentary basins of up to 4 km thickness (Bohnhoff et al, 2001). Furthermore, these branches have a dominant sinistral strike-slip faulting (LePichon and Angelier, 1979;Huchon et al, 1982;Huguen et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

“…In a second step, this layer was subdivided into three segments along the Hellenic arc from West to East. The dip of each segment was adjusted following structural models of the forearc region that were derived from wide angle seismics (Bohnhoff et al, 2001;Brönner, 2003), surface wave and receiver function analysis (Li et al, 2003;Meier et al, 2004a;Endrun et al, 2004) and moving source profiles (Truffert et al, 1993). Furthermore, we implement data from a Moho map of the Eastern Mediterranean (Marone et al, 2003).…”

Section: Data Base and Procedures Appliedmentioning

confidence: 99%

“…Lambeck, 1995) that are not yet fully understood. At the central and eastern part of the forearc indications for remnants of oceanic crust were identified (Bohnhoff et al, 2001;Brönner, 2003;Meier et al, 2004a). Figure 1 gives an overview on the tectonic setting of the Aegean-Anatolian region with the Hellenic subduction zone.…”

Section: Introductionmentioning

confidence: 99%

“…Below the Libyan Sea an accretionary wedge with a sedimentary cover of up to 15 km is located between the active and passive continental margins. Recent microseismicity and surface wave studies (Meier et al, 2004b) as well as active seismic lines (Truffert et al, 1993;Bohnhoff et al, 2001;Brönner, 2003) allowed to refine the structural model along the Hellenic subduction zone (see inset in Figure 1) exemplifying the complex geometry along a strongly curved plate boundary. The overall seismic activity of the Hellenic subduction zone is small compared to other subduction zones as can be observed from global earthquake catalogues.…”

Section: Introductionmentioning

confidence: 99%

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Deformation and stress regimes in the Hellenic subduction zone from focal Mechanisms

2005

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Fault plane solutions for earthquakes in the central Hellenic arc are analysed to determine the deformation and stress regimes in the Hellenic subduction zone in the vicinity of Crete. Fault mechanisms for earthquakes recorded by various networks or contained in global catalogues are collected. In addition, 34 fault plane solutions are determined for events recorded by our own local temporary network on central Crete in [2000][2001]. The entire data set of 264 source mechanisms is examined for types of faulting and spatial clustering of mechanisms. Eight regions with significantly varying characteristic types of faulting are identified of which the upper (Aegean) plate includes four. Three regions contain interplate seismicity along the Hellenic arc from west to east and all events below are identified to occur within the subducting African lithosphere. We perform stress tensor inversion to each of the subsets in order to determine the stress field. Results indicate a uniform N-NNE direction of relative plate motion between the Ionian Sea and Rhodes resulting in orthogonal convergence in the western forearc and oblique (40-50°) subduction in the eastern forearc. There, the plate boundary migrates towards the SE resulting in left-lateral strike-slip faulting that extends to onshore Eastern Crete. N110°E trending normal faulting in the Aegean plate at this part is in accordance with this model. Along-arc extension is observed on Western Crete. Fault plane solutions for earthquakes within the dipping African lithosphere indicate that slab pull is the dominant force within the subduction process and interpreted to be responsible for the roll-back of the Hellenic subduction zone.

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Section: Discussionmentioning

confidence: 99%

Section: Data Base and Procedures Appliedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Deformation and stress regimes in the Hellenic subduction zone from focal Mechanisms

2005

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“…This can also provide an explanation for the pressure conditions of emplacement to the Sanbagawa crustal units. The emplacement pressure of about 1 GPa (Figure 12) corresponds to the depth of Moho beneath a typical convergent margin [e.g., Zhao et al, 1990;Bohnhoff et al, 2001;Bostock et al, 2002]. It is likely that the buoyant force will no longer be sufficient to cause further exhumation once the partly serpentinized peridotite becomes surrounded by relatively low-density crustal rocks.…”

Section: Serpentine Formation: a Trigger To Exhumationmentioning

confidence: 99%

Structural and petrological constraints on the tectonic evolution of the garnet‐lherzolite facies Higashi‐akaishi peridotite body, Sanbagawa belt, SW Japan

Mizukami

Wallis

2005

Tectonics

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[1] The Higashi-akaishi peridotite body in the Sanbagawa metamorphic belt is a unique example of a kilometer-scale body including garnet-lherzolite facies rocks from an oceanic subduction-type orogen. In this body, four distinct deformational phases D 1 , D 2 , D 3 , and D 4 can be defined. The tectonic significance of D 1 is unclear. Microstructural observations and application of garnet-orthopyroxene geothermobarometry suggest that D 2 took place during high-temperature subduction up to depths of $100 km (from 2.3 GPa to above 2.8 GPa at temperature of 700-800°C) or more. D 3 represents a major phase of exhumation. After exhumation the Higashi-akaishi body became juxtaposed with the adjacent Besshi and Eclogite units at a depth of around 35 km (1 GPa). The common history of the two units after D 3 is shown by the intertectonic growth of tremolite between D 3 and D 4 that corresponds to a stage of intertectonic growth of plagioclase in the Besshi and Eclogite units. Both the spatial distribution and the estimated pressuretemperature (P-T) conditions of this intertectonic phase of mineral growth in the different units are in excellent agreement. The development of an antigorite schistosity during the late stage of D 2 indicates an anticlockwise P-T path with cooling at depths of around 100 km. The association of the antigorite-bearing fabric and the onset of exhumation after the D 2 stage suggest that the density decrease due to antigorite formation may have been sufficient to trigger the exhumation of dense ultramafic body from UHP conditions in subduction zones. Syn-D 2 water introduction and the anticlockwise P-T path are expected when convection in the mantle wedge brings peridotite toward a subduction boundary through mantle wedge or when peridotite is dragged down along a subduction boundary that is progressively cooling immediately after initiation of subduction. Citation: Mizukami, T., and S. R. Wallis (2005), Structural and petrological constraints on the tectonic evolution of the garnet-lherzolite facies Higashi-akaishi peridotite body, Sanbagawa belt, SW Japan, Tectonics, 24, TC6012,

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Structure and anisotropy of the crust in the Cyclades, Greece, using receiver functions constrained by in situ rock textural data

et al. 2016

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Seismic anisotropy data are often used to resolve rock textures and deformation in the crust based on compilations of rock properties that may not be representative of the local geology. In this paper, we use teleseismic receiver functions jointly with in situ rock property data to constrain the seismic structure and anisotropy of the crust in the Cyclades, Greece, located in the back‐arc region of the Hellenic subduction zone. The receiver function data indicate that the Moho is relatively flat at 25 km depth toward the south and deepens to 33 km in the north, consistent with previous studies, and reveal an intracrustal discontinuity at depths varying from 3 to 11 km, mostly observed in the south central Aegean. Harmonic decomposition of the receiver functions further indicates the presence of both shallow and deep crustal anisotropy related to crustal structures. We model synthetic receiver functions based on constraints from in situ rock properties that we measured using the electron backscatter diffraction technique. Our results indicate that the shallow upper crustal layer is characterized by metapelites with ~5% anisotropy, underlain by a 20 km thick and possibly anisotropic layer of high‐pressure rocks comprising blueschist and eclogite and/or restitic crust resulting from magmatism. This study demonstrates the importance of rock textural data in the interpretation of seismic velocity profiles.

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Crustal investigation of the Hellenic subduction zone using wide aperture seismic data

Cited by 140 publications

References 29 publications

Deformation and stress regimes in the Hellenic subduction zone from focal Mechanisms

Deformation and stress regimes in the Hellenic subduction zone from focal Mechanisms

Structural and petrological constraints on the tectonic evolution of the garnet‐lherzolite facies Higashi‐akaishi peridotite body, Sanbagawa belt, SW Japan

Structure and anisotropy of the crust in the Cyclades, Greece, using receiver functions constrained by in situ rock textural data

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